In shoe constructions in which waterproof breathable uppers are used, it is convenient to attach the combination to an insole. But due to construction and cost considerations, it is not feasible to bring the upper and liner across the bottom of the shoe. Accordingly, an insole supplement, frequently called an insole gasket, is used to bridge the area not covered by the combination, and to provide a waterproof buffer between the insole and the outer sole. However, it is difficult to bond across the opening. Many gasket materials tend to wrinkle during bonding. Others are too limp and pliant. Many need to have adhesive applied thus creating a separate step. In addition to these requirements, the insole gasket needs to be waterproof.
It would be desirable to have a waterproof insole gasket that is flexible but stiff so that it can be easily positioned in place without wrinkling or become misshaped, that is strong but lightweight, that is self-adhering so that a separate adhesive need not be applied thus making use of solvent and means for solvent removal unnecessary.